These rings have not only been noticed by the illiterate, but by philosophers and learned characters, who have advanced two opinions respecting them. Some, among whom are Dr. Priestly and Mr. Jessop, upon practical and scientific observations, attributed them to lightning, but their experiments did not prove altogether satisfactory. Drs. Wollaston, Withering, and others, who had _duly_ examined these spots, ascribed them to the growth of fungi, which opinion seems undoubtedly the best.--The rings vary in size and shape, some having seven yards of _bare_, with a patch of _green_ grass a foot broad in the middle; others, of various sizes, are encompassed with grass much greener than that in the interior. It is rather remarkable that no beasts will eat of them, although some persons suppose that _sheep_ will greedily devour the _grass_. Shakspeare thus speaks in his Tempest: "Ye elves of hills, brooks, stagnant lakes, and groves, And ye that on the sands with printless foot, Do chase the ebbing Neptune, and do fly him When he comes back; you demi puppets that By moonshine do the _green sour_ ringlets make, Whereof the _ewe not bites_, and you whose pastime Is to make midnight mushrooms----." The following story is well known in Carmarthenshire:--A farmer going out one morning very early to fetch his horses from pasture, heard some delicious music, far sweeter he thought (no doubt) than ever bard produced from his _telyn_ (harp); and being allured by it, as we read of men being allured of old by the enchanting voices of Sirens, he proceeded to the place whence the strains seemed to issue, and in a sequestered retreat beheld the elves footing it merrily. Wishing perhaps to obtain more extensive knowledge of these "dear little creatures," he had the magnanimity to enter the ring, with the intention of joining their matachin, and soon had his desire gratified, for there they kept him, dancing away, night and day, without intermission. His relatives at home were at a loss to know what had become of him, and immediately concluded that he had terminated his existence, or had gone on a journey; but days, weeks, and months rolled on, and no farmer appeared, nor were any tidings heard respecting him, until it chanced one day that a man passing by the lonely spot, saw him knocking his legs about as if he was bereft of his reason; and going up to him, inquired what caused him to be so merry, which broke the spell; and the farmer, as if waking out of a dream, exclaimed, "O dear! where are my horses?" and stepping out of the magical circle, fell down, and mingled his dust with the earth: no wonder, for he had been dancing without nourishment or food for more than a twelvemonth. If every fair dancer joined the Tylwyth teg's dance, how many beings would be danced out of the world?